Biogenic synthesis and characterization of silver nanoparticles using aqueous leaf extract ofScoparia dulcisL. and assessment of their antimicrobial property

Naturally occurring phytochemicals serve as an excellent substitute in synthesizing nanomaterials. A process for the synthesis of silver nanoparticles (AgNPs) from the aqueous leaf extract of naturally occurringScoparia dulcisis described here. The extracellular formation of AgNPs occurred within few minutes upon incubation ofS. dulcisaqueous leaf extract (0.1 mL) (100% extract) with silver nitrate (2 mM AgNO3) at 90 degrees C for 30 min, is first of its kind work. The appearance of bright yellow color with lambda(max)420 nm confirm the formation of AgNPs. Zeta potential and X-ray diffraction (XRD) studies reveal stable AgNPs (-22.7 mV) and characteristic spectra for silver. Fourier transform infrared (FTIR) spectroscopy indicate the involvement of carboxyl, amine and hydroxyl groups in the synthetic process. Transmission electron microscopy (TEM) show the spherical nature of AgNPs measuring 3-18 nm in size. Additional characterization using Dynamic light scattering (DLS) revealed the average particle size distribution of AgNPs as around 8.2 nm. Further antimicrobial testing through agar disc diffusion plate method indicated that silver nanoparticles are potentially active against pathogenic bacteria such asPseudomonas aeruginosa,Escherichia coli,Bacillus subtilisandStaphylococcus aureusand are only optimally active against fungi such asAspergillus nigerandCandida albicansand measurement of minimal inhibition concentration by standard microdilution method. In conclusion, the study suggests that successful synthesis of green nanoparticles (AgNPs) using aqueousS. dulcisleaf extract is simple, rapid, environmentally benign and economical. Moreover, these synthesized silver nanoparticles showed antimicrobial activity.